A typical gas turbine that is used to generate electrical power includes an axial compressor at the front, one or more combustors downstream from the compressor, and a turbine at the rear. Ambient air may be supplied to the compressor, and rotating blades and stationary vanes in the compressor progressively impart kinetic energy to the working fluid (air) to produce a compressed working fluid at a highly energized state. The compressed working fluid exits the compressor and flows towards a head end of combustor where it reverses direction at an end cover and flows through the one or more nozzles into a primary combustion zone that is defined within a combustion chamber in each combustor. The compressed working fluid mixes with fuel in the one or more fuel nozzles and/or within the combustion chamber and ignites to generate combustion gases having a high temperature and pressure. The combustion gases expand in the turbine to produce work. For example, expansion of the combustion gases in the turbine may rotate a shaft connected to a generator to produce electricity.
A typical combustor includes an end cover coupled to a compressor discharge casing, an annular cap assembly that extends radially and axially within the compressor discharge casing, an annular combustion liner that extends downstream from the cap assembly, and a transition piece having an annular transition duct that extends between the combustion liner and a first stage of stationary nozzles. The stationary nozzles are positioned generally adjacent to an inlet to the turbine section.
In a particular combustor design, one or more LLI injectors, also known as late lean injectors, are circumferentially arranged around and mounted to the combustion liner downstream from the fuel nozzles and/or the primary combustion zone. Various fluid conduits and fluid couplings extend within the compressor discharge casing to route fuel from a fuel source to the LLI injectors. A portion of the compressed working fluid exiting the compressor is routed through the LLI injectors to mix with the fuel to produce a lean fuel-air mixture. The lean fuel-air mixture may then be injected into the combustion chamber for additional combustion in a secondary combustion zone to raise the combustion gas temperature and increase the thermodynamic efficiency of the combustor. The late lean injectors are effective at increasing combustion gas temperatures without producing a corresponding increase in the production of undesirable emissions such as oxides of nitrogen (NOX). The late lean injectors are particularly beneficial for reducing NOX during base load and/or turndown operation of the gas turbine.
Installation and removal of a combustor having late lean injection hardware to and/or from a space limited environment such as the compressor discharge casing of the gas turbine has become increasingly challenging due in part to a decreasing footprint of many current gas turbine designs. For example, access to the various fluid couplings, fluid conduits and/or the LLI injectors may be restricted. In addition, valuable man hours required to assemble or disassemble the various late lean injection components to the combustor while mounted to the gas turbine may be excessive due to the difficulty related to proper installation and removal of the late lean injection hardware. Therefore, a system for providing fuel to the combustor that reduces assembly time and complexity of the combustor would be useful.